Inductive Proximity Switch With Segmented Receiver Coil
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing inductive proximity switches lack simplicity and reliability in detecting the zero crossing of their output voltage when a target moves, particularly in distinguishing the position of a metal target relative to a switching point without causing multiple false switches due to noise.
Innovation Solution
An inductive proximity switch design featuring a transmitter coil and a receiver coil with symmetrical segments connected in series, a resonant circuit, and a signal processing unit including an oscillator, hysteresis comparator, and optional low pass filter, which generates a magnetic field and processes signals to indicate the target's position relative to the switching point, reducing noise-induced multiple switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard inductive proximity switch design is used, then the sensor can detect metal targets, but it suffers from noise sensitivity causing multiple false switches
Solution Approach 1:
The receiver coil is divided into two symmetrical segments connected in series with opposite orientations. This segmentation allows the sensor to detect the position of the target relative to the switching point by comparing the induced voltages in each segment, thereby reducing noise-induced false switches.
Solution Approach 2:
A hysteresis comparator is used in the signal processing unit to provide feedback that stabilizes the switching behavior. The hysteresis effect ensures that small noise fluctuations around the switching point do not cause multiple false switches, improving reliability.
2Measurement precision
If the receiver coil has asymmetrical segments, then the switching point detection may be simplified, but the sensor cannot accurately distinguish target position relative to the switching point
Solution Approach 1:
While the overall structure maintains symmetry, the two segments of the receiver coil are connected in series with opposite orientations, creating an effective asymmetry in the signal processing. This allows the hysteresis comparator to accurately detect when the target crosses the switching point by comparing the differential voltages from the two segments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides reliable and robust detection of a metal target's position with reduced noise sensitivity, maintaining accurate position information even after the target has moved outside the sensor region, and allows for efficient identification of target presence upon power-on.
Implementation Method 1
An oscillator is configured to excite the transmitter coil, thereby inducing a voltage in the receiver coil
Implementation Method 2
When a conductive target gets near to the sensor, eddy currents will be induced. The eddy currents (mainly) generate a counter magnetic field that reduces the total flux in the transmitter and receiver coil underneath the target
Implementation Method 3
An oscillator advantageously excites the resonant circuit comprising the transmitter coil and the parallel capacitor on its resonant frequency, thus generating high current in the transmitter coil
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to an inductive proximity switch. The object of the invention to present a very simplified inductive position sensor, which can be reliably used for detecting a zero crossing of its output voltage when a target moves by will be solved by an inductive proximity switch comprising a transmitter coil, a receiver coil, an integrated circuit for excitation of the transmitter coil and a signal processing unit for processing a received signal from the receiver coil, wherein an oscillator excites a resonant circuit comprising the transmitter coil and a parallel capacitor for inducing a voltage in the receiver coil, wherein the receiver coil comprises two symmetrical segments with opposite orientation that are connected in series, wherein the transmitter coil surrounds the segments of the receiver coil or the transmitter coil is surrounded by the segments of the receiver coil.